Railway signaling system.



L. V. LEWS L I. S. HOLLIDAY.

RAILWAY SIGNALING SYSTEM.

APPLIGATION FILED JULY 7, 1911.

l L. Patented Feb.6,1912.

ne it tj GHS T THE UNON SVHTGH z SEG-NAL GOMPANY, 0F SNSSVALE,

'Lewis end ,izens or the United *ftiveljg et Ld ffewood the county orfille- Pennsy Vania, have inend .useful improve om* is specification.

- relates to epparetus'ior use current signaling systems Ways both etthe lines of ,hich cre included in the path renti. More pcrticufrom theseine g drewi' g is it diagramtc'o e portion o an electric ed 'thereto esignaling rswing, 'L designates ic railway the 'track ded byinsel-ations 4; 'n n, it is un: ,e f3 he lince of track rails e c cenitforthe propu i is must be provided propulsion current fils' here shown,

' eens comprises inductive bonds t3, lei, i6, which bonds are p eerslolyel? Ke shown find described in United i ters Petenthlo. 838,916, grantedThollon on Dec. 18, 190. Briefly each these bonds comprises e iron coreupon which :ire Wound sevterr err electric conductor. The

et the bonds are contrziclt rails edpropulsion current in its passagethrough the Winding of each hond iloWs in "e ends and out at the middlepoint, er the middle 'point and out et the ends, hf t therefore it' theiiow of propulsion current is equal in the two lines ot rails, the

Sijoccication ci' Letters Fateci.

, Patented 3, itali?,

eerzal re. @7369.

iron core of the bond will not loe megnetized by this current, Hence thebond Will not be inductive to the propulsion current when the propulsioncurrent is alternating. But since the alternating signaling current,hereinafter explenedytends to liow through the winding' of each hondfrom end to end, the bonds will he inductive 'to this currenty andtherefore impede the ioW of signaling current from one line of rails tothe other.

We here not shown the genera-tor for the propulsion current nor theremainder of the circuit for the propulsion current; these elements areso Well understood as to require no further illustration or description.

Each lclocl section is provided with e track 4circuit coinprisingcsusual the track rails (or portions of there) of the block section, esource of signaling current, and e relay. As here shown, the source ofcurrent for two acent block sections, for example block sections A andB, is a. transformer 5 Whose primary 6 is connected With a source 8, 8,designate relays for the block sec- @tions A and E respectively, whichrelays may he of any desired t-yge which will respond to the signalingcurrent :md not to the propulsion current in their normal or usuel control. olf their signals.

S, S, designate rail my signals, controlled by relays En", S, in :Lusual nd Well known manner..

included in each track circuitlhetween the secondary of thetransformer-"end the track rails is u, resistance, which hay he eitherinductive or non-inductireln ,the ficcoi'npenying drawing, ll is theresistance i'or the track circuit of block section A, and l2 is theresistance for the track circuit of block section B. These resistcncesmay be employed to limit the discharged signaling current from 'thetransformer secondary when the track mils of e, block section areocctmiecl` hy cer or train, or they may he employed to aiiect the phaseof the signaling current supplied to the relay by the track circuit, orthey may be employed for both ol these purposes or for other purposes. l

As shown in the accompanying drawing, the resistance 11 (ron-inductiveor inductive) in the track circuit of block section A. is divided intotwo substantially equal portions 11"L and 11b, one of which portions isincluded in each of the two leads between the transformer secondary andthe track rails. Similarly, the resistance 12 tor the track circuit ofblock section B is divided into two substantially equal portions 12a and12b, one 'of which is included in each of the leads between thetransformer secondary and the track rails. With this arrangement, therewill be no iiow of current between the middle points of bonds 13 and 14,even when the total resistances 11 and 12 are unequal, for the rea sonthat these middle points will always have the same potential, and thispotential will be the same as that of the middle point of thetransformer secondary 7. lhis is evident, from the fact that the circuitbetween. each terminal of the transformer secondary and the middle pointot "ach oi' the bonds includes a half winding the bond and a half of thetotal resistance 11 or 12. With a car 17 in block section B as indicatedin the drawing, although the bond lt will be shunted by the car, thepotential of the middle point ot this bond will still be equal to thatof the middle point of the secondary .7 for the reason that there yareequal resistances 12l and 12b between thcterminals of the secondary 7and the middle point of bond 141. Hence the two track circuits will beentirely free from interference with each other, regardless of whetheror not one or the other or both are occupied by a car, except for suchslight action as may occur within the windings of the trans-- former.

It is often advantageous that the resistances 11 and 12 should beinductive. When such is the case, the two portions 11 and 11b arepreferably in the form ot two coils wound on one magnetic core 19, andthe two portions 12a and `12b are preferably in the form of two coils onanother magnetic core 20, as illustrated diagrammatically in thedrawing. With this construction, the total impedance of either pair ofcoils 11 or 12 vmay be varied by varying the reluctance of the commonmagnetic circuit for each pair, the impedance of the two coils on eachcore being always equal. The coils are connected with the track railsand with the source of signaling current in such manners that the4magnetic iuX induced in each core by signaling current flowing in thetwo coils ,Wound thereon will be all in the same direction, so that thecoils are inductive ,to the signaling current; but that the magneticilus induce.dI

by propulsion current in the two coils will be in opposite directionsand will therefore be neutralized, so that the core will not bemagnetized by the propulsion current2 and so that when the propulsioncurrent is alternating its tlow will not be impeded by the windings.This arrangement of the coils will be readily understood by reference tothe accompanying drawing.

When the coils 11a, 11b, 12a and 12b are connected as just described,they will automatically compensate for conditions caused by unbalancedpropulsion current inthe two lines of rails. When unbalancing occurs,that is, when more propulsion current flows in one line of rails of ablock section than in the other line of rails, there will be morepropulsion current in one Vhalt of the winding of the bonds 13, 14, 15and 16 than in the other half, and consequently the cores of the bondswill become magnetized. This magnetization will lower the impedance ofthe bond to the signaling current, allowing more signaling current toflow through the bond and thereby having a tendency to reduce thevoltage of the signaling current at the relay. But at such times, theflow of propulsion current in the two coils on each core 19 and 20 willalso be unbalanced, and the propulsion current will magnetize' thesecores, thereby reducing their impedance 'to the signaling current andincreasing the voltage of the signaling current impressed on the trackrails. The voltage of the signaling current at the relays will thus bemaintained substantially constant in spite of unbalancing of thepropulsion current.

Having thus described our invention, what we claim is:

1. In a railway signaling system, two adjacent block sections, a sourceof alternating signaling current, a transformer whose primary isconnected with the source of alternating signaling current and whosesecondary is connected across the track rails of both block sections,andtwo substantially equal resistances connected respectively betweenthe transformer secondary and each rail of one of the block sections;

2. ln a railway signaling system, two adjacent block sections, a sourceof alternating signaling current, a transformer whose primary isconnected with the source of alternating signaling current and whosesecondary is connected across the track rails of both block sections,and two substantially equal resistances connected respectively betweenthe transformer secondary and each rail of one of the block sections,and twd substantially equal resistances connected respectively betweenthe transformer secondary and each rail of the other block section.

3. ln a signaling system for electric railways the track rails ol' whichare included isa (gli

lli-

nordsee in the circuit for the propulsion current, two adjacent blocksections divided by insulation in` the track rails, means forpermitting4 propulsion current to ilow trom the rails of either of thesaid block sections to the rails of the other block section, a source ofalternating signaling current, a transformer whose primary is connectedwith the source of signaling' current and whose secondary is connectedacross the track rails of both of said block sections, two substantiallyequal resistances connected respectively between the transformersecondary and each rail of one et the block sections, and twosubstantially equal resistances connected respectively between thetransformer secondary and each rail of the other block section.

in a signaling4 system for elect-ric railways the track rails of weichare included in the circuit for the propulsion current, two adjacentblock sections divided by insulation in the track rails, means forpermitting propulsion current to dow from the rails of either of thesaid block sections to the rails of the other block section, a trackcircuit tor each block section each 01" which track circuits includesthe opposite lines ot' rails of the block se tion, a source ofalternating signaling, current, a transformer whose primary is connectedwith the source ot signalcurrent and whose secondary is connectedacrossl the track rails of both. of said block sections, twosubstantially equal 4resistanees connecten respectively between thetransformer secondary and each rail oi.3 one of the block sections, andtwo substantially equal resistances connected respectively between thetransformer secondary and each rail of the` other block section.

5. in a. signaling' system for electric railways, the track, rails ofwhich are included in 'the circuit for the propulsion current, twoadjacent block sections divided by insulations. in the track rails,means for permit-- ting the propulsion current to flow from the rails ofeither block section to the rails of the'other block section, a sourceof alternating` signaling current, a transformer having 'its primaryconnected with the source of signaling current and its secondaryconnected across the track rails of both block sections, twosubstantially equal inductive resistances wound in the same direction onone magnetic core and interposed respectively between the secondary andeach track rail of one ot' the block sections, and two substantiallyequal inductive resistances wound in the same direction on anothermagnetic core and interposed respectively between the metil secondaryand each track rail of the other block section.

6. .in a signaling system tor electric railways the. track rails ofwhich are included y in the circuit for the propulsion current, twoadjacent block sections divided by insulation in the track rails, meansrfor permitting the propulsion current to tiow from the rails of oneblock section to the rails ci the other block section, said meanscomprising an .inductive winding connected across the opposite rails ofeach block section, and conductor connecting the middle points ot thesaid windins, a source of alternating signaling current, a transformerwhose primary is connected with the source of signaling,- current andwhose secondary is connected across the track rails of both blocksections, two substantially equal resistances interposed between thesecondaryand each track rail respectively of one of said block sections,and two substantially equal resistanccs interposed. between thesecondary and each track rail respectively of the other block section.

7. l'n a signaling system for electric railways the track rails of whichare included in the circuit for the propulsion current, two adjacentblock sections divided by insulation in the track rails, means forpermitting the propulsion current to flow from the rails of one blocksection to the rails of the other block section, said means comprisingan inductive windingr connected across the opposite rails of each blocksection and a oonductor connecting the middle points or the saidwindings, a source of alternating signaling current, a. transformerwhose primary is connected with the source of signaling current and`whose secondary is connected across the track rails of both blocksections, t-wo substantially equal inductive resistances wound in thesame direction on one magnetic core and interposed respectively betweenthe secondary and each track rail of one of the block sections, and twosubstantially equal inductive resistances wound in the same direction onanother magnetic core and interposed respectively between the secondaryand each track rail of the other block section.

In testimony whereof we atx our signatures in presence of two witnesses.

LLOYD V. LEWIS. JHN S. HULLIDAY l/Vitnesses:

CnAs. E. McCoy, C. R. BEALL.

Sill

